1. Field of the Invention
The disclosed embodiment relates to a rotating electric machine.
2. Description of the Related Art
Japanese Examined Utility Model Registration Application Publication No. 7-36459 discloses a permanent-field-magnet rotor including a laminated iron core, rectangular permanent magnets, punched holes formed in the iron core, and nonmagnetic reinforcing members. The laminated iron core includes a connection portion and magnetic pole portions. The connection portion has an annular shape and surrounds a rotation shaft. The magnetic pole portions, each having a sectorial shape, are disposed outside the connection portion, and the number of the magnetic pole portions corresponds to the number of poles. The connection portion and the magnetic pole portions are integrated with each other. The permanent magnets are disposed between the magnetic pole portions. The punched holes are formed so as to extend in the magnetic pole portions and the connection portion, and each of the punched holes has enlarged portions at both ends thereof. The reinforcing members are inserted into the punched holes so as to fill the punched holes therewith.
Rare earth magnets such as neodymium magnets are widely used as permanent magnets included in a rotor of a rotating electric machine. By using a rare earth magnet as a permanent magnet of a rotor, the size of the permanent magnet can be reduced because rare earth magnets have a high magnetic flux density. However, rare earth magnets are expensive. On the other hand, when using an inexpensive magnet such as a ferrite magnet as the permanent magnet, it is necessary to increase the volume of the permanent magnet because ferrite magnets have a magnetic flux density lower than that of rare earth magnets.
In the rotor of the related art described above, the punched holes for reducing leakage flux are formed between the permanent magnets. Therefore, there is a problem in that the length of the permanent magnet in the radial direction and the length of the permanent magnet in a direction perpendicular to the radial direction are limited and therefore it is difficult to increase the volume of the permanent magnet without increasing the diameter of the rotor.